Retrofit of Non-Metallic Chain & Flight Grit Collectors at a Municipal WWTP-K.G.Matzen

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Project Name: Retrofit of Non-Metallic Chain & Flight Grit Collectors at a Municipal WWTP

Year: 2025

Capacity: 150,000 m³/d, 1 grit chamber

Product Type: Upgrade of Non-Metallic Chain & Flight Grit Collector System

Client Pain Points:

• Since commissioning, the existing grit collector system showed recurring failures:

• Frequent scraper misalignment and detachment disrupting grit discharge

• Chain breakage, deformation, and shear pin activations during certain cycles

• Sediment buildup in the sump causing suction pipe clogging

• High turbulence and vortex flow preventing effective grit settling

• Material aging and chain desynchronization resulting in derailment

• Limited maintenance access and high operational risk

Cause Analysis:

Symptoms	Root Causes
Scraper misalignment/fall	Overload + uneven force + material aging
Chain breakage	Excessive drag load + fatigue + unstable transmission
Shear pin failure	Off-center load + sudden reactive force
Grit layer buildup	Strong vortex, poor settling conditions
Sump clogging	Insufficient pump/suction power
Material deformation	Long-term fatigue in non-metallic chains

Upgrades:

• Chain System Reinforcement:

Tightened and segmented inspection of chain components

Repaired or replaced damaged links

Upgraded tensioning devices to eliminate slack

• Axial Alignment Adjustment:

Realigned shafts to ensure torque balance

Ensured chain sprockets operate smoothly

• Vortex Suppression Measures:

Installed top-level steel flow diverters at the chamber inlet

Minimized turbulence to enhance grit sedimentation

• Air Agitation System Enhancement:

Added bypass from existing air lines

Installed dual-layer air nozzle system over grit sump

Enabled periodic manual air scouring to prevent hardened deposits

Project Outcomes:

Chain derailment frequency reduced by >85%

Shear pin false activation nearly eliminated

Suction pipe clogging frequency dropped by >70%

Achieved stable unattended operation

Lowered O&M workload and improved operational safety

Extended system life and enhanced treatment reliability

Technical Highlights:

Retrofit Area	Technical Feature
Chain System	Reinforced tensioning and load distribution
Material Upgrades	Anti-aging coating and structural enhancement
Transmission Design	Coaxial torque transmission with added supports
Cleaning System	Dual-layer nozzles + air scour agitation